Abstract: Process for applying a coating of ceramic material on a substrate by plasma spraying. The material to be sprayed, which is incorporated in the plasma jet, includes a chemical compound one constituent of which is a non-metallic element from the group N, C, B or from main groups VI or VII of the periodic classification, which decomposes, at least partially, in an inert environment before reaching the melting point and which is present in the solid phase in the applied state. To improve the process so that the chemical compound contained in the material can be applied to the substrate stoichiometrically, i.e., undecomposed, and form an impermeable, adherent, stable coating, the non-metallic element is incorporated in the plasma jet, in addition to the material to be sprayed, in a free form, not bound to a foreign element.